Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
  • H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
  • G01R31/52—Testing for short-circuits, leakage current or ground faults
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
  • H02H7/18—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for batteries; for accumulators
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
  • H02J7/60—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements

Definitions

• the invention relates to the field of energy storage systems, insulation monitoring devices, and the monitoring and/or checking of the energy storage systems.
• the invention relates to a method, a controller, and an Insulation Monitoring Device (IMD) for checking an earth-fault-free condition of an energy storage system, and to the energy storage system.
• IMD Insulation Monitoring Device
• Energy storage systems comprising battery packs are increasingly used in very complex products, such as high-voltage DC-links for propulsion applications, for example.
• the battery packs each may comprise two or more battery cells being arranged electrically in series, for example.
• the propulsion applications may be used in electric vehicles, e.g., in on-road and/or in off-road vehicles, such as e.g. mining trucks, trains, trams, and subways.
• IMDs Insulation Monitoring Devices
• a first aspect relates to a method for checking an earth-fault-free condition of an energy storage system.
• the energy storage system comprises a first battery pack having a first pole, a second pole, and at least two battery cells electrically arranged in series between the first pole and the second pole.
• the method comprises: receiving a first voltage signal being representative of a first voltage between the second pole and a ground potential; determining a first condition as being fulfilled when the first voltage signal raises above a first voltage threshold and determining the first condition as not being fulfilled when the first voltage signal does not raise above the first voltage threshold; sending a first control signal to a first switch, wherein the first switch is configured to connect the second pole to the ground potential via a second resistor having a predetermined second resistance upon receiving the first control signal; determining a second condition as being fulfilled when the first voltage signal falls below a predetermined second voltage threshold after the first switch connected the second pole to the ground potential and determining the second condition as not being fulfilled when the first voltage signal does not fall below the predetermined second voltage threshold after the first switch connected the second pole to the ground potential; determining the first battery pack as being in the earth-fault-free condition when the first condition and the second condition are fulfilled; determining the first battery pack as not being in the earth-fault-free condition when the first condition and/or the second condition are not fulfilled;
• a second aspect relates to a controller for checking the earth-fault-free condition of the energy storage system.
• the controller comprises a memory for storing one or more voltage values and/or one or more voltage thresholds, and a processor being communicatively coupled with the memory and being configured to carry out the method as described above and in the following.
• a third aspect relates to an Insulation Monitoring Device (IMD) for checking the earth-fault-free condition of the energy storage system.
• the IMD comprises: a first resistor having a predetermined first resistance; a first voltmeter for being electrically coupled to the second pole and the ground potential, and being configured to measure a first voltage between the second pole and the ground potential; a second resistor having a predetermined second resistance and being configured for providing an electric coupling of the second pole to the ground potential; a first switch electrically coupled to the second resistor and being configured for establishing or interrupting the electric coupling of the second pole to the ground potential depending on a state of the first switch; and a controller as described above and in the following and being communicatively coupled to the first voltmeter and the first switch.
• the first resistor may be implemented within a further voltmeter arranged in the first battery pack, for example.
• the first pole may be electrically coupled to the ground potential via a first resistor having a predetermined first resistance and/or may be configured to electrically couple the first pole to the ground potential.
• a fourth aspect relates to the energy storage system for providing electric energy to a load.
• the energy storage system comprises: the first battery pack having the first pole, the second pole, and at least two battery cells electrically arranged in series between the first pole and the second pole; and the IMD as described above and in the following, wherein the first pole is electrically coupled to the ground potential via the first resistor of the insulation monitoring device, the first voltmeter of the insulation monitoring device is electrically coupled to the second pole and the ground potential, and is configured to measure the first voltage between the second pole and the ground potential, and the first switch electrically coupled to the second resistor and is configured for establishing or interrupting the electric coupling of the second pole to the ground potential depending on the state of the first switch.
• the above aspects contribute to omit, reduce, and/or make easier to detect the risks mentioned above with respect to the background of the invention.
• the method, controller, and energy storage system are scalable, robust, controllable, and/or evaluable by a controller.
• the disclosed solution is much faster than state-of-the-art systems in terms of detection time and maintenance free.
• the controller carrying out the method represents a novel passive insulation monitoring device for battery applications. Its key contributions are a fast detection time, no current source is required for test signal injection and adjustable measurement evaluation on a standard control unit.
• the insulation monitoring functionality is implemented with two sets of resistors, the first switch, a voltage measurement and an evaluation algorithm represented by the described method.
• the voltage needed for checking the battery packs is received from the battery pack, which is monitored, and is utilized for the described test sequence. So, no separate energy source is needed for checking the battery packs.
• the test sequence comprises a first phase ("Phase I") in which it is checked whether the first condition is fulfilled and a second phase (“Phase II”) in which it is checked whether the second condition is fulfilled.
• the test sequence has a third phase (“Phase III”), as explained below.
• the advantage of the inventive method is that by very simple design enhancements a mitigation feature to prevent harm is incorporated, by detecting single earth faults in battery systems. Due to the described procedure, it is easy to locate the exact fault location and disconnect the faulty part. Furthermore, the conditions of the battery packs can be monitored in terms of a quantitative insulation resistance tracking, in particular in Phase I & II.
• the first voltage may be measured by the first voltmeter.
• the first voltmeter may generate the first voltage signal depending on the measurement of the first voltage such that the first voltage signal is representative of the first voltage.
• the first voltage may be measured and the first voltage signal may be correspondingly generated continuously when carrying out the method.
• the first and second voltage thresholds may be predetermined in advance, e.g., depending on the first and, respectively, second resistances.
• the one or more voltage values may be encoded in the first voltage signal and/or in any further voltage signals.
• the first resistor may be integrated within the further voltmeter.
• the energy storage system may be configured for providing electric energy to a load.
• the load may be an electric motor, e.g., a motor for driving an electric vehicle.
• the electric vehicle may be configured for transporting one or more persons and/or goods.
• the electric vehicle may be an on-road or an off-road vehicle, e.g., a mining truck, a train, a tram, or a subway.
• the battery packs of the energy storage system may be referred to as propulsion battery packs of the electric vehicle.
• the IMD mentioned above may be referred to as first IMD.
• the first IMD may comprise a housing in which its components are arranged.
• the controller may be configured for receiving the first voltage signal, for checking the first and/or second condition, for sending the control signal(s) to the switch(es), and in case for initiating the safety measure.
• the energy storage system in particular the battery pack, may be operated normally.
• the energy storage system and in particular the battery pack may be used for providing the propulsion energy for the electric vehicle.
• the safety measure may comprise or may be one or more safety measures out of a group of safety measures, the group comprising: deactivating the energy storage system, deactivating the battery pack, and sending a warning signal to an operator of the energy storage system, e.g., of the vehicle.
• the energy storage system comprises a second switch being electrically arranged in series with the battery cells between the first pole and the second pole and wherein the second switch is configured for interrupting or establishing the serial connection of the battery cells between the first pole and the second pole
• the method comprises before receiving the first voltage signal: sending a second control signal to the second switch of the first battery pack, wherein the second switch is configured to establish the serial connection of the battery cells between the two poles of the first battery pack upon receiving the second control signal, wherein it is determined whether the first condition is fulfilled a predetermined duration after the second switch established the serial connection of the battery cells between the two poles of the first battery pack.
• the predetermined duration may be in the range of 0.01 s to 1.000 s, e.g., of 0.5 s to 60 s, e.g., of 1 s to 30 s.
• the second switch of the first battery pack may be electrically arranged between the first pole and the battery cells, between the battery cells and the second pole, or between two of the battery cells of the first battery pack. When the second switch of the first battery pack is open, the serial connection of the battery cells between the poles of the first battery pack is interrupted.
• the energy storage system comprises a second battery pack electrically arranged in parallel with the first battery pack, wherein the second battery pack is configured in correspondence to the first battery pack, and wherein a second switch of the second battery pack interrupts a serial connection of battery cells of the second battery pack between two poles of the second battery pack while the earth-fault-free condition of the first battery pack is checked
• the method comprises: sending a third control signal to the second switch of the first battery pack after checking the earth-fault-free condition of the first battery pack, wherein the second switch of the first battery pack is configured to interrupt the serial connection of the battery cells between the two poles of the first battery pack upon receiving the third control signal; sending the second control signal to the second switch of the second battery pack, wherein the second switch of the second battery pack is configured to establish the serial connection of the battery cells between the two poles of the second battery pack upon receiving the second control signal; and checking the earth-fault-free condition of the second battery pack.
• the battery system comprises more than two battery packs
• these battery packs may be checked one after the other after checking the first and second battery packs. So, all battery packs of the battery system may be checked with respect to the earth-fault-free condition one after the other.
• the serial connections of the battery cells between the two poles of all the battery packs which are not currently checked may be interrupted by the corresponding second switches upon receiving the corresponding third control signals.
• the earth-fault-free condition of the second or in case any further battery packs may be checked in the same way as the earth-fault-free condition of the first battery pack is checked, in particular via monitoring the first voltage signal before and after closing the corresponding first switch.
• That the second battery pack is configured in correspondence to the first battery pack may mean that the second battery pack has the same structure and comparable components as the first battery pack.
• the second battery pack and each further battery pack mentioned in this description may comprise its own first pole, second pole, and two or more battery cells being electrically arranged in series between the first pole and the second pole.
• the energy storage system comprises a converter configured for electrically coupling at least the first battery pack to the load and a first contactor configured for electrically coupling the first battery pack to the converter
• the method comprises, before receiving the first voltage signal: sending a fourth control signal to the first contactor, wherein the first contactor is configured for interrupting the electrical connection between the first battery pack and the converter upon receiving the fourth control signal; and determining whether the first condition is fulfilled after the first contactor interrupted the electrical connection of the first battery pack to the first converter, and in case after the second switch established the serial connection of the battery cells between the two poles of the first battery pack.
• the energy storage system in particular the first battery pack
• the energy storage system cannot be operated normally anymore, but may be checked for the earth-fault-free condition.
• the electrical connection between the first battery pack and the converter may be established again by the first contactor and the energy storage system, in particular the first battery pack, can be operated normally again, if the first battery pack is determined as being in its earth-fault-free condition.
• the energy storage system comprises at least the paralleled first and second battery packs, the converter is configured to electrically couple the first and second battery packs to the load, the first contactor is configured to electrically couple the first and second battery packs to the converter, and the first contactor is configured for interrupting the electrical connection between the first and second battery packs and the converter upon receiving the fourth control signal.
• the energy storage system comprises a second branch having a second contactor and at least one further battery pack, wherein the second contactor is configured for establishing or interrupting an electrical connection of the further battery pack of the second branch to the converter, sending the fourth control signal to the second contactor after checking the earth-fault-free condition of the battery packs of the first branch, wherein the second contactor is configured for interrupting the electrical connection between the further battery pack and the converter upon receiving the fourth control signal; and checking the earth-fault-free condition of the further battery pack of the second branch after the second contactor interrupted the electrical connection of the further battery pack to the converter based on a second voltage signal being representative of a second voltage between second pole of the further battery pack and the ground potential.
• the first branch and the second branch may be electrically arranged in series.
• the earth-fault-free condition of the battery pack of the second branch may be checked in correspondence to the first or second battery packs but based on the second voltage signal instead of the first voltage signal.
• the second branch comprises two or more of the further battery packs.
• the further battery packs may be electrically arranged in parallel.
• the paralleled further battery packs of the second branch are paralleled with respect to each other only. In particular, they are not paralleled with respect to single battery packs of the first branch.
• the paralleled further battery packs may be checked with respect to the earth-fault-free condition one after the other.
• the energy storage system comprises the second switch being electrically arranged in series with the battery cells between the first pole and the second pole, and the second switch is configured for interrupting or establishing the serial connection of the battery cells between the first pole and the second pole.
• the energy storage system comprises the second battery pack electrically arranged in parallel with the first battery pack, wherein the second battery pack is configured in correspondence to the first battery pack.
• the energy storage system comprises the converter configured for electrically coupling at least the first battery pack to the load, and the first contactor electrically coupled to the converter and being configured to electrically couple the first battery pack to the converter.
• the energy storage system comprises: at least the paralleled first and second battery packs, wherein the converter is configured for electrically coupling the first and second battery packs to the load, wherein the first contactor is configured for electrically coupling the first and second battery packs to the converter, and wherein the first contactor is configured for establishing or interrupting the electrical connection between the first and second battery packs and the converter.
• the first contactor and the paralleled first and second battery packs and in case any further battery packs being electrically arranged in parallel with the first and second battery packs form the first branch of the energy storage system
• the energy storage system comprises the second branch having the second contactor and at least one further battery pack, wherein the second contactor is configured to establish or interrupt an electrical connection of the further battery pack of the second branch to the converter.
• a structure and functionality of the second branch may correspond to the structure and, respectively, functionality of the first branch.
• the second branch may comprise two or more of the further battery packs being electrically arranged in parallel with each other.
• the method comprises, after determining whether the second condition is fulfilled: sending a fifth control signal to the first contactor, wherein the first contactor is configured for establishing the electrical connection between the first battery pack and in case any further battery pack of the energy storage system and the converter upon receiving the fourth control signal; determining whether the first voltage signal raises above a predetermined third voltage threshold; and determining the first battery pack and, respectively, in case any further battery pack of the energy storage system as not being in the earth-fault-free condition when the first voltage signal raises above the predetermined third voltage threshold.
• the energy storage system comprises a second insulation monitoring device, wherein the second insulation monitoring device is electrically coupled to the second branch and is configured for checking an earth-fault-free condition of the further battery packs of the second branch.
• a structure and functionality of the second insulation monitoring device may correspond to the structure and functionality of the first insulation monitoring device.
• the second insulation monitoring device comprises: a third resistor having a predetermined third resistance, wherein a second pole of one of the further battery packs of the second branch is electrically coupled to the ground potential via the third resistor; a second voltmeter being electrically coupled to a first pole of the corresponding further battery pack and the ground potential, and being configured to measure a second voltage between the first pole of the corresponding further battery pack and the ground potential; a fourth resistor having a predetermined fourth resistance and being configured for providing an electric coupling of the first pole of the corresponding further battery pack to the ground potential; and a third switch electrically coupled to the fourth resistor and being configured for establishing or interrupting the electric coupling of the second pole of the corresponding further battery pack to the ground potential depending on a state of the third switch.
• the second IMD may comprise a housing in which its components are arranged.
• the third resistor may be integrated within the further voltmeter, wherein in this case the further voltmeter may be integrated within one of the further battery packs. So, the first IMD may be assigned to the first branch and the second IMD may be assigned to the second branch for checking the battery packs of the corresponding branch with respect to their earth-fault-free conditions.
• the converter has a first terminal and a second terminal configured for electrically coupling the converter to the load, the first terminal is coupled to the ground potential via a fifth resistor, the second terminal is coupled to the ground potential via a sixth resistor, and a resistance of the fifth resistor is different from a resistance of the sixth resistor.
• These features may represent an asymmetric soft grounding of the converter.
• the asymmetric soft grounding may contribute to that an earth fault arsing during normal operation of the energy storage system causes a detectable shift in the first voltage signal in Phase III, in other words the third phase.
• the method may be embodied as a computer program.
• the computer program may comprise computer-readable instruction which may cause the controller to carry out the method when being executed by the processor of the controller.
• the computer program may be stored on a computer-readable medium.
• the computer-readable medium may be a floppy disk, a hard disk, an USB (Universal Serial Bus) storage device, a RAM (Random Access Memory), a ROM (Read Only Memory), an EPROM (Erasable Programmable Read Only Memory) or a FLASH memory.
• the computer readable medium may also be a data communication network, e.g. the Internet, which allows downloading a program code.
• the computer-readable medium may be a non-transitory or transitory medium.
• Fig. 1 shows a block diagram of an exemplary embodiment of an energy storage system 20.
• the energy storage system 20 is configured for providing electric energy to a load (not shown).
• the load may be an electric motor, e.g., a motor for driving an electric vehicle (not shown).
• the electric vehicle may be configured for transporting one or more persons and/or goods.
• the electric vehicle may be a mining truck, a train, a tram, or a subway.
• the energy storage system 20 comprises a first battery pack 22, a converter 24, and a first Insulation Monitoring Device (IMD) 40.
• the first battery pack 22 has a first pole 30, a second pole 32, and at least two battery cells 28 electrically arranged in series between the first pole 20 and the second pole 32.
• the first battery pack 22 and in case any further battery pack of the energy storage system 20 may be referred to as propulsion battery packs of the electric vehicle.
• the converter 24 is an electric converter, such as a rectifier and/or inverter.
• the first battery pack 22 is electrically couplable to the converter 24 via a contactor 26.
• the first contactor 26 is configured to electrically couple the first battery pack 22 to the converter 24 or to decouple the first battery pack 22 from the converter 24 depending on state of the contactor 26.
• the electric coupling between the first battery pack 22 and the converter 24 is established in a closed state of the contactor 26 and the electric coupling between the first battery pack 22 and the converter 24 is interrupted in an open state of the contactor 26.
• the contactor 26 may be or may comprise a relay.
• the first IMD 40 is configured for checking an earth-fault-free condition of the energy storage system 20.
• the first IMD 40 comprises a first resistor 42, a first voltmeter 44, a second resistor 46, a first switch 48, and a controller 50.
• the first resistor 42 has a predetermined first resistance.
• the first resistor 42 is electrically coupled to the first pole 30 and to a ground potential 34.
• the first resistor 42 electrically couples the first pole 30 to the ground potential 34.
• the first resistor 42 may be implemented within a further voltmeter 98 (see figure 4 ).
• the first voltmeter 44 is electrically coupled to the second pole 32 and to the ground potential 34.
• the first voltmeter 44 is configured to measure a first voltage between the second pole 32 and the ground potential 34.
• the second resistor 46 has a predetermined second resistance.
• the second resistor 46 is electrically coupled to the second pole 32 and is couplable to the ground potential 34 via the first switch 48. So, the second resistor 46 electrically couples the second pole 32 to the ground potential 34 depending on a state of the first switch 48.
• the first switch 48 may comprise a relay. Power contacts of the first switch 48 are electrically coupled to the second resistor 46 and, respectively, to the ground potential 34. A control contact of the first switch 48 is coupled to the controller 50.
• the first switch 48 is configured for establishing or interrupting the electric coupling of the second pole 32 to the ground potential 34 depending on a state of the first switch 48. In particular, when the first switch 48 is in an open state, the electric coupling of the second pole 32 to the ground potential 34 is interrupted, and when the first switch 48 is in a closed state, the electric coupling of the second pole 32 to the ground potential 34 is established.
• the first IMD 48 may comprise a housing (not shown) in which its components are arranged.
• the controller 50 may be a component of the IMD 40.
• the controller 50 is communicatively coupled to the first voltmeter 44 and to the first switch 48.
• the controller 50 is configured for checking the earth-fault-free condition of the energy storage system 20.
• the controller 50 comprises a memory (not shown) for storing one or more voltage values and/or one or more voltage thresholds, and a processor (not shown) being communicatively coupled with the memory and being configured to carry out the method as described below with respect to figure 8 .
• Fig. 2 shows a block diagram of an exemplary embodiment of an energy storage system 20.
• the energy storage system 20 shown in figure 2 may widely correspond to the energy storage system 20 explained with respect to figure 1 . Therefore and in order to process provide a concise description, only those features of the energy storage system 20 shown in figure 2 are described in the following, in which the energy storage system 20 shown in figure 2 differs from the energy storage system 20 explained with respect to figure 1 .
• the energy storage system 20 comprises a second battery pack 60 electrically arranged in parallel with the first battery pack 22.
• the energy storage system 20 may comprise even more battery packs electrically arranged in parallel with the first and second battery pack 22, 60, e.g., a third battery pack 62.
• the second and third battery packs 60, 62 and in case any further battery packs may be configured in correspondence to the first battery pack 22. That the second and third battery packs 60, 62 and in case any further battery packs are configured in correspondence to the first battery pack 22 may mean that the second and third battery packs 60, 62 and in case any further battery packs each have the same structure and comparable components as the first battery pack 22.
• the second and third battery packs 60, 62 and in case any further battery packs mentioned in this description may comprise its own first pole, second pole, and two or more battery cells being electrically arranged in series between the corresponding first and second poles.
• the energy storage system 20, in particular the first battery pack 22 may comprise one or more second switches 58 being electrically arranged in series with the battery cells 28 of the first battery pack 22 between the first pole 30 and the second pole 32 of the first battery pack 22.
• Each of the second switches 58 of the first battery pack 22 is configured for interrupting or establishing the serial connection of the battery cells 28 of the first battery pack 22 between the first and second poles of the first battery pack 22.
• the second switch 58 may be arranged anywhere within the serial connection of the battery cells 28 between the first and second poles 30, 32, for example between the first pole 30 and the battery cells 28, or between the battery cells 28 and the second pole 32.
• the second and the third and in case any further battery packs 60, 62 each comprises at least one respective second switch 58 for interrupting or establishing the serial connection of the corresponding battery cells 28 between the first and second poles of the corresponding battery pack 60, 62.
• the converter 24 is configured for electrically coupling the first, second, and third battery packs 22, 60, 62 to the load.
• the first contactor 26 is configured for electrically coupling the first, second, and third battery packs 22, 60, 62 to the converter 24.
• the first contactor 26 is configured for establishing or interrupting the electrical connection between the first, second, and third battery packs 22, 60, 62 and the converter 24.
• a first filter 52 may be electrically arranged between the converter 24 and the first contactor 26.
• the first filter 52 may comprise a first inductor 54 and a first capacitor 56.
• the first inductor 54 may be electrically arranged in series between the first contactor 26 and the converter 24.
• the first capacitor 56 may be electrically arranged in parallel to the first inductor 54.
• the first filter 52 is configured for establishing a voltage conversion together with the converter 24, as it is known in the art.
• Fig. 3 shows a block diagram of an exemplary embodiment of an energy storage system 20.
• the energy storage system 20 shown in figure 3 may widely correspond to the energy storage system 20 explained with respect to figure 2 . Therefore and in order to process provide a concise description, only those features of the energy storage system 20 shown in figure 3 are described in the following, in which the energy storage system 20 shown in figure 3 differs from the energy storage system 20 explained with respect to figure 2 .
• the first contactor 26 and the paralleled first, second, and third battery packs 22, 60, 62 and in case any further battery packs being electrically arranged in parallel with the first and second battery packs 22, 60 form a first branch 64 of the energy storage system 20.
• the energy storage system 20 may comprise a second branch 66 having a second IMD 80, a second contactor 70 and at least one further battery pack 68, preferably two or more further battery packs 68 electrically arranged in parallel with respect to each other.
• the second contactor 70 is configured to establish or interrupt an electrical connection of the further battery packs 68 of the second branch 66 to the converter 24.
• a structure and functionality of the second branch 66 may correspond to the structure and, respectively, functionality of the first branch 64.
• the second insulation monitoring device 80 is electrically coupled to the second branch 66.
• the second insulation monitoring device 80 is configured for checking an earth-fault-free condition of the further battery packs 68 of the second branch 66.
• the second insulation monitoring device 80 may comprise a third resistor 82, a second voltmeter 84, a fourth resistor 86, and a third switch 88.
• the third resistor 82 may have a predetermined third resistance.
• the first poles 30 of the further battery packs 68 may be electrically coupled to the ground potential 34 via the third resistor 82.
• the second voltmeter 84 may be electrically coupled to the first poles 30 of the further battery packs 68 and to the ground potential 34.
• the second voltmeter 84 may being configured to measure a second voltage between the first poles 30 of the further battery packs 68 and the ground potential 34.
• the fourth resistor 86 has a predetermined fourth resistance.
• the fourth resistor 86 is configured for providing an electric coupling of the second poles 32 of the further battery packs 68 to the ground potential 34.
• Power contacts of the third switch 88 may be electrically coupled to the fourth resistor 86 and to the ground potential 34, whereas a control contact of the third switch 88 may be communicatively coupled to the controller 50.
• the third switch 88 may be configured for establishing or interrupting the electric coupling of the second poles 32 of the further battery packs 68 to the ground potential 34 depending on a state of the third switch 88.
• the second IMD 80 may comprise a housing in which its components are arranged.
• the third resistor 82 may be integrated within the further voltmeter 98 (see figure 4 ).
• a second filter 72 may be electrically arranged between the converter 24 and the second contactor 70.
• the second filter 72 may comprise a second inductor 74 and a second capacitor 76.
• the second inductor 74 may be electrically arranged in series between the second contactor 70 and the converter 24.
• the second capacitor 76 may be electrically arranged in parallel to the second inductor 74.
• the second filter 72 is configured for establishing a voltage conversion together with the converter 24, as it is known in the art.
• the converter 24 has a first terminal 102 and a second terminal 104 configured for electrically coupling the converter 24 to the load.
• the first terminal 102 may be electrically coupled to the ground potential 34 via a fifth resistor 106 and the second terminal 104 may be electrically coupled to the ground potential 34 via a sixth resistor 108, wherein a resistance of the fifth resistor 106 is different from a resistance of the sixth resistor 108.
• the fifth and sixth resistors 106, 108 represent an asymmetric soft grounding of the converter 24.
• Fig. 4 shows a block diagram of an exemplary embodiment of a voltmeter, e.g., of a further voltmeter 98 independent from the first or second voltmeter 44, 84.
• the first resistor 42 and/or the third resistor 82 may be implemented within a respective further voltmeter 98.
• the further voltmeter 98 may be arranged within one of the battery packs 22, 60, 62, 68 for measuring the voltage provided by the corresponding battery pack 22, 60, 62, 68.
• the further voltmeter 98 may comprise two or more further resistors 90 electrically arranged in series with the first or, respectively, third resistor 42, 82.
• the first or, respectively, third resistor 42, 82 may be electrically coupled to the ground potential 34 via one or more of these further resistors 90.
• the further voltmeter 98 may further comprise a first amplifier 92, a second amplifier 94, and a third amplifier 96.
• the amplifiers 92, 94, 96 provide in combination with the resistors 42, 90 a voltage measurement value, which is representative for the differential input voltage on the terminals of the further voltmeter 98.
• Fig. 5 shows a block diagram of an exemplary embodiment an insulation monitoring device, e.g., the first IMD 40.
• the second IMD 80 may be configured correspondingly.
• the first IMD 40 shown in figure 5 may be used as an alternative to the first IMD 40 described with respect to figures 1 , 2 , and/or 3.
• the first IMD 40 is configured for checking the earth-fault-free condition of the energy storage system 20.
• the first IMD 40 comprises two first resistors 42, the first voltmeter 44, the second resistor 46, the first switch 48, and the controller 50.
• the first resistors 42 have the predetermined first resistance.
• the first poles 30 of the battery packs 22, 60, 62 of the first branch 64 may be electrically coupled to the ground potential 34 while the first IMD 40.
• the first resistors 42 are electrically coupled to the second poles 32 of the battery packs 22, 60, 62 of the first branch 64 and to the first switch 48.
• the first voltmeter 44 is electrically coupled to the second poles 32 of the battery packs 22, 60, 62 of the first branch 64 and to the ground potential 34.
• the first voltmeter 44 is configured to measure a first voltage between the second pole 32 and the ground potential 34.
• the second resistor 46 has the predetermined second resistance.
• the second resistor 46 is electrically coupled to the second poles 32 of the battery packs 22, 60, 62 of the first branch 64 via the first resistors 42 and to the ground potential 34.
• the first switch 48 may form an electrical bypass around the second resistor 46. For example, the second resistor 46 may be bypassed by the first switch 48 when the first switch 48 is in its closed state and the second resistor 46 may not be bypassed by the first switch 48 when the first switch 48 is in its open state.
• Fig. 6 shows an example of a first diagram with a first voltage signal 100 in case of the energy storage system 20 being in an earth-fault-free condition.
• An ordinate of the first diagram shows a ratio of an IMD voltage U IMD to a battery pack voltage U pack and an abscissa of the first diagram shows the time.
• the IMD voltage U IMD corresponds to the first voltage measured by the first voltmeter 44.
• the battery pack voltage U pack corresponds to the voltage of the serial connected battery cells 28 of the battery pack which is currently checked, i.e., the first battery pack 22 between a first and a fourth point of time t1, t4.
• the battery pack voltage U pack may be measured or may be received from a Battery Management System (BMS) (not shown) of the energy storage system 20.
• BMS Battery Management System
• the first voltage signal 100 may be generated by the first voltmeter 44 and may be representative for the first voltage. So, the first voltmeter 44 may generate the first voltage signal 100 depending on the measurement of the first voltage such that the first voltage signal 100 is representative of the first voltage.
• the battery packs 22, 60, 62 of the first branch 64 may be checked with respect to their earth-fault-free condition based on the first voltage signal 100. The first voltage may be measured and the first voltage signal 100 may be generated continuously when checking the battery packs 22, 60, 62 of the first branch 64 with respect to the earth-fault-free condition.
• a first phase (“Phase I”) PH1 may range from the first point in time t1 to a second point in time t2.
• a second phase (“Phase II”) PH2 may range from a third point in time t3 to the fourth point in time t4.
• the first battery pack 22 may be checked during the first phase PH1 starting at the first point in time t1 and during the second phase PH2 starting at the third point in time t3.
• the first and second phases PH1, PH2 may be repeated to check the second battery pack 60.
• the first and second phases PH1, PH2 may be repeated for every remaining battery pack 62 of the energy storage system 20.
• the first voltage signal 100 raises above a predetermined first voltage threshold TH1 within the first phase PH1 and drops below the predetermined second voltage threshold TH2 in the second phase PH2.
• This principle may repeat for every earth-fault-free battery pack 60, 62 of the first branch 64.
• An exemplary calculation of the first and second voltage thresholds is explained in more detail below with respect to figure 8 .
• Fig. 7 shows an example of a second diagram showing the first voltage signal 100 in case of the energy storage system 20 not being in the earth-fault-free condition.
• the second diagram itself, in particular the ordinate and the abscissa, corresponds to the first diagram, wherein the first voltage signal 100 in the second diagram differs from the first voltage signal 100 in the second diagram.
• the first voltage signal 100 does not raise above the first voltage threshold UT1 in the first phase PH1 ranging from the first to the second points of time t1, t2.
• the first battery pack 22 has an earth-fault and thereby a faulty insulation. So, the first battery pack 22 is not in an earth-fault-free condition.
• the first voltage signal 100 raises above the first voltage threshold UT1, and drops below the second voltage threshold UT2 within the following second phase PH2.
• the second battery pack is 60 is in an earth-fault-free condition.
• the first and second diagram contain the first voltage signal 100 as an example.
• the detection principles of the first and second diagrams explained in the foregoing may be easily transferred to a second voltage signal (not shown) which may be generated by the second voltmeter 84 and which is representative for the second voltage. So, an earth-fault-free condition of the further battery packs 68 of the second branch 66 may be determined based on the second voltage signal in the same way as the earth-fault-free condition of the battery packs 22, 60, 62 of the first branch 64 are determined based on the first voltage signal 100.
• Fig. 8 shows an example of a third diagram describing a relationship between an Estimated Isolation Resistance (EIR) and a ratio of the IMD voltage U IMD to the battery pack voltage U pack .
• EIR Estimated Isolation Resistance
• R g 100 k ⁇ is set as an exemplary insulation resistance of an earth-fault-free battery pack, e.g., of the first battery pack 22.
• the exemplary insulation resistance R g may be measured between a midpoint of the serial connected battery cells 28 of the corresponding battery pack 22, 60, 62, 68.
• First measurements 110 are carried out during the first phase PH1.
• the first measurements 110 may be above the exemplary insulation resistance R g in a first allowable region 114 and below the exemplary insulation resistance R g outside of the first allowable region 114 before.
• Second measurements 112 are carried out during the second phase PH2.
• the second measurements 112 may be above the exemplary insulation resistance R g in a second allowable region 116 and then below the exemplary insulation resistance R g outside of the second allowable region 116.
• the first and second voltage thresholds UT1, UT2 may be predetermined in advance e.g., depending on the first and, respectively, second resistances R 1 , R 2 , with a graphic or implicit method as shown in Fig. 8 and may be stored on the memory of the controller 50, for example.
• Fig. 9 shows a flow diagram of an exemplary embodiment of a method for checking an earth-fault-free condition of the energy storage system 20, in particular of one or more of the battery packs 22, 60, 62, 68 of the energy storage system 20, e.g., of the first battery pack 22.
• a fourth control signal may be sent to the first contactor 26, wherein the first contactor 26 is configured for interrupting the electrical connection between the first, second, and third battery packs 22 and the converter 24 upon receiving the fourth control signal.
• a second control signal may be sent to the second switch 58 of the battery pack which is currently checked with respect to its earth-fault-free condition, i.e., the first battery pack 22.
• the second switch 58 may be configured to establish the serial connection of the battery cells 28 between the two poles 30, 32 of the first battery pack 22 upon receiving the second control signal.
• a third control signal may be sent to the second switches 58 of the other battery packs 60, 62 of the first branch 64, wherein the second switches 58 are configured to interrupt a serial connection of the battery cells 28 of the corresponding battery pack 60, 62 while the earth-fault-free condition of the first battery pack 22 is checked,
• the first voltage signal 100 being representative of the first voltage between the second pole 32 and the ground potential 34 may be received, e.g., by the controller 50.
• a first condition may be determined as being fulfilled, e.g., by the controller 50, when the first voltage signal 100 raises above the first voltage threshold UT1 within the first phase PH1 and the first condition may be determined as not being fulfilled when the first voltage signal 100 does not raise above the first voltage threshold UT1 within the first phase PH1.
• it may be determined whether the first condition is fulfilled or not a predetermined duration after the second switch 58 established the serial connection of the battery cells 28 between the two poles 30, 32 of the first battery pack 22.
• the predetermined duration may be in the range of 0.01 s to 1.000 s, e.g., of 0.5 s to 60 s, e.g., of 1 s to 30 s.
• a first control signal may be sent to the first switch 48, e.g., by the controller 50, wherein the first switch 48 is configured to connect the second pole 32 of the first battery pack 22 to the ground potential 34 via the second resistor 46 having the predetermined second resistance R 2 upon receiving the first control signal.
• a second condition may be determined as being fulfilled when the first voltage signal 100 falls below the predetermined second voltage threshold UT2 after the first switch 48 connected the second pole 32 of the first battery pack 22 to the ground potential 34 in the second phase PH2, and the second condition may be determined as not being fulfilled when the first voltage signal 100 does not fall below the predetermined second voltage threshold UT2 after the first switch 48 connected the second pole 32 of the first battery pack 22 to the ground potential 34 in the second phase PH2.
• the first battery pack 22 may be determined as being in the earth-fault-free condition when the first condition and the second condition are fulfilled, or the first battery pack 22 may be determined as not being in the earth-fault-free condition when the first condition and/or the second condition are not fulfilled.
• the method may proceed in a step S14.
• the method may proceed in a step S16.
• step S14 the energy storage system 20, in particular the first battery pack 22, may be operated normally.
• the energy storage system 20 and in particular the first battery pack 22 may be used for providing the propulsion energy for the electric vehicle.
• another battery pack 60, 62 of the first branch 64 or one of the further battery packs 68 of the second branch 66 may be checked with respect to their earth-fault-free conditions, e.g., by repeatedly carrying out the steps S2 to S 12.
• the safety measure may comprise or may be one or more safety measures out of a group of safety measures, the group comprising: deactivating the energy storage system 20, deactivating the first battery pack 22, and sending a warning signal to an operator of the energy storage system, e.g., of the vehicle.
• another battery pack 60, 62 of the first branch 64 or one of the further battery packs 68 of the second branch 66 may be checked with respect to their earth-fault-free conditions, e.g., by repeatedly carrying out the steps S2 to S 12.
• the third control signal may be sent to the second switch 58 of the first battery pack 22, wherein the second switch 58 of the first battery pack 22 is configured to interrupt the serial connection of the battery cells 28 of the first battery pack 22 upon receiving the third control signal.
• the second control signal may be sent to the second switch 58 of the second battery pack 60, in correspondence to step S2 described above, wherein the second switch 58 of the second battery pack 60 is configured to establish the serial connection of the battery cells 28 of the second battery pack 60 upon receiving the second control signal.
• the earth-fault-free condition of the second battery pack 60 may be checked, e.g., in correspondence with steps S4 to S 16 described above.
• the first branch 64 comprises more than two battery packs 20, 60, as e.g. described with respect to figure 2
• these battery packs 62 may be checked one after the other after checking the first and second battery packs 20, 60. So, all battery packs 20, 60, 62 of the first branch 64 may be checked with respect to the earth-fault-free condition one after the other.
• the serial connections of the battery cells 28 between the two poles 30, 32 of all the battery packs 20, 60, 62 which are not currently checked may be interrupted by the corresponding second switches 58 upon receiving the corresponding third control signals.
• the earth-fault-free condition of the second or in case any further battery packs 60, 62 may be checked in the same way as the earth-fault-free condition of the first battery pack 22 is checked, in particular via monitoring the first voltage signal 100 before and after closing the corresponding first switch 48.
• a fourth control signal may be sent to the second contactor 70 after checking the earth-fault-free condition of the battery packs 22, 60, 62 of the first branch 64.
• the second contactor 70 may be configured for interrupting the electrical connection between the further battery packs 68 and the converter 24 upon receiving the fourth control signal.
• the earth-fault-free condition of the further battery packs 68 of the second branch 66 may be checked one after the other in correspondence to the above explained checking of the earth-fault-free condition of the battery packs 22, 60, 62 of the first branch 64 based on a second voltage signal (not shown) being representative of the second voltage between first poles 30 of the further battery packs 68 and the ground potential 34.
• the analysis of the second voltage signal may correspond to the analysis of the first voltage signal 100. In particular, it may be checked whether second voltage signal raises above the first voltage threshold UT1 in the first phase PH1 and falls below the second voltage threshold UT2 in the second phase PH2.
• the first branch 64 and the second branch may 66 be electrically arranged in series.
• the earth-fault-free condition of the battery packs 68 of the second branch 66 may be checked in correspondence to the first or second battery packs 22, 62, but based on the second voltage signal instead of the first voltage signal.
• the second branch 66 comprises two or more of the further battery packs 68.
• the further battery packs 68 may be electrically arranged in parallel.
• the paralleled further battery packs 68 of the second branch 66 are paralleled with respect to each other only. In particular, they are not paralleled with respect to single battery packs 22, 60, 62 of the first branch 64.
• the paralleled further battery packs 68 may be checked with respect to the earth-fault-free condition one after the other.
• Fig. 10 shows a flow diagram of an exemplary embodiment of a method for checking an earth-fault-free condition of the energy storage system 20.
• the method explained with respect to figure 10 may be carried out after the method explained with respect to figure 9 has been carried out with the result that all battery packs 22, 60, 62, 68 of the energy storage system 20 are in the earth-fault-free condition.
• the method explained with respect to figure 10 implements a third phase of checking the earth-fault-free condition of the energy storage system 20, in particular during a normal operation of the energy storage system 20.
• a fifth control signal may be sent to the first contactor 26, and in case to the second contactor 70, wherein the contactors 26, 70 are configured to establishing the electrical connection between the battery packs 22, 60, 62, 68 of the energy storage system 20 and the converter 24 upon receiving the fourth control signal.
• the energy storage system 20 may be in its normal operation. The method explained with respect to figure 10 may be carried out continuously and/or repeatedly as long as the energy storage system 20 is operated normally.
• a step S22 the first voltage signal 100 and in case the second voltage signal may be received.
• a step S24 it may be checked whether the first and/or second voltage signals 100 raise above a predetermined third voltage threshold.
• the third voltage threshold may be determined empirically, by simulation and/or by calculation.
• the first battery pack 22 and, respectively, in case any further battery pack 60, 62, 68 of the energy storage system 20 may be determined as not being in the earth-fault-free condition when the first and/or, respectively, second voltage signal 100 raises above the predetermined third voltage threshold.
• the method proceeds in a step S28. Otherwise, the method proceeds in step S26.
• step S26 the energy storage system 20, in particular the battery packs 22, 60, 62, 68 may be operated normally.
• the method of figure 10 may proceed in S22 by monitoring the first and/or second voltage signals 100 continuously. This monitoring phase during normal operation of the energy storage system 20 may be referred to as third phase. Alternatively, the method may be terminated.
• step S28 the at least one safety measure may be initiated.
• the method explained with respect to figure 9 and the method explained with respect to figure 10 may be implemented within the same algorithm and as such may form one single method only.
• the method(s) may be embodied as computer program(s).
• the computer program(s) may comprise computer-readable instructions which may cause the controller 50 to carry out the method when being executed by the processor of the controller 50.
• the computer program may be stored on a computer-readable medium.
• the computer-readable medium may be a floppy disk, a hard disk, an USB (Universal Serial Bus) storage device, a RAM (Random Access Memory), a ROM (Read Only Memory), an EPROM (Erasable Programmable Read Only Memory) or a FLASH memory.
• the computer readable medium may also be a data communication network, e.g. the Internet, which allows downloading a program code.
• the computer-readable medium may be a non-transitory or transitory medium.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Charge And Discharge Circuits For Batteries Or The Like (AREA)

Priority Applications (2)

Applications Claiming Priority (1)

Publications (1)

Family

ID=91853684

Family Applications (1)

Country Status (2)

Citations (4)

• 2024
  • 2024-07-04 EP EP24186623.5A patent/EP4675875A1/fr active Pending
• 2025
  • 2025-07-02 WO PCT/EP2025/068750 patent/WO2026008667A1/fr active Pending

Patent Citations (4)

Also Published As

Similar Documents

Legal Events